In recent years, with advancement of semiconductor miniaturization process techniques, memory apparatuses (memories) have been remarkably developed to achieve higher densities and larger capacities. In the field of nonvolatile memory apparatuses, technical progresses of FLASH memories are remarkable, and its cost is being reduced. Especially, the cost of the FLASH memories has been reduced year by year. Under this background, systems using the FLASH memories are widely used in many fields including program storage devices to be built into home appliances or the like, data storage devices for storing data of music, images, motion pictures, etc. It is expected that the nonvolatile memory apparatuses are applicable to all fields, by further reducing the cost. The cost reduction of the conventional nonvolatile memory apparatuses is accomplished by the progresses of manufacture techniques of the FLASH memories. However, these days, it is said that there is a limitation on miniaturization of the FLASH memories using floating gates. Under the circumstances, novel nonvolatile memory apparatuses have attracted attention because of a prospect for achievement of further cell area reduction and further cost reduction. As typical novel nonvolatile memory apparatuses, there are FeRAM using ferroelectric, MRAM using magnetism, PRAM using phase change, ReRAM which is a resistance variable memory apparatus, etc.
In manufacture of memory elements (resistance variable elements) of the resistance variable memory apparatuses, a resistance variable material having binary based transition metal oxide or perovskite oxide is used for a resistance variable layer. The resistance variable element is adapted to store data in a nonvolatile manner based on electric resistances (e.g., high-resistance state and low-resistance state) of the resistance variable layer. The bias condition for causing the resistance variable layer to switch the resistance state is varied according to the resistance variable material. For example, there is known a bipolar type resistance variable material which causes switching between two values by changing a direction of the electric pulse applied to both sides of the resistance variable layer. Also, there is known a unipolar type resistance variable material which causes switching between two values based on difference in the magnitude (voltage) or pulse duration (time) of the electric pulse having the same polarity. For example, Patent document 1 discloses a resistance variable memory apparatus using the unipolar type resistance variable material and a unidirectional diode.
Patent document 2 discloses a cross-point resistance variable memory apparatus using the bipolar type resistance variable elements. In the resistance variable memory apparatus, when writing data, Vpp is applied to a selected bit line, Vss (0V) is applied to a selected word line, and ½Vpp is applied to a non-selected word line and to a non-selected bit line. When erasing data, Vpp is applied to a selected word line, Vss (0V) is applied to a selected bit line, and Vpp/2 is applied to a non-selected word line and to a non-selected bit line.    Patent document 1: Japanese Laid-Open Patent Application Publication No. 2001-127263    Patent document 2: Japanese Laid-Open Patent Application Publication No. 2006-203098